一种单晶高温合金的泊松比的各向异性

Anisotropy of Poisson’s ratio of a Ni Base Single Crystal Superalloy

摘要:

以一种第三代单晶高温合金为实验材料,通过籽晶法制备了[001][100](2个指数分别为一次和二次取向)和[011][110] 2种取向的单晶料板,采用敲击共振法测试了从室温到1100 ℃范围内第1种试样的Young’s模量和剪切模量及第2种试样的剪切模量,根据测试结果,计算出单晶高温合金的3个弹性常数C11、C12和C44,从而得到单晶高温合金各个取向的泊松比。绘制了泊松比的最大值及最小值的三维取向分布图,分析了泊松比随晶体取向的变化规律。当一次取向沿着[001]和[111]时,泊松比在面内具有各向同性。当一次取向沿着[011]时,泊松比随着二次取向的变化而显著改变,二次取向在以[110]为中心的约60°的范围内泊松比为负值,在其他角度范围内为正值,且在[100]时具有最大值。

Abstract:

The anisotropy of Poisson’s ratio of single crystal superalloy is essential to understand its mechanical behavior, e.g. calculating the contact stress between blade tenon and turbine disc. However, it’s difficult to determine the Poisson’s ratio of single crystal superalloy of every orientation. In this paper, one simple experimental method is employed to measure the stiffness constants and then the Poisson’s ratio of different orientation is calculated. The slabs of a third generation single crystal superalloy in two orientations á001?á100? and á011?á110? are prepared by seeding technique in Bridgman method. The Young’s modulus and shear modulus of the first specimen and the shear modulus of the second specimen are measured by resonance method from room temperature to 1100 ℃. The three stiffness constants C11, C12 and C44 of this superalloy are calculated from the measured moduli. The Poisson’s ratio in any orientation can be calculated based on the stiffness constants. Further, the 3D distribution map of maximum and minimum of Poisson’s ratio of every primary orientation can be drawn, so the distribution feature of Poisson’s ratio in 3D space can be acquired conveniently. When the primary orientations are along á001? and á111?, the Poisson’s ratio in plane is isotropy with secondary orientation. When the primary orientation is along á011?, the Poisson’s ratio demonstrates significant anisotropy with secondary orientation, the Poisson’s ratio reach minimum with secondary orientation á110? with negative value, while maximum is obtained in secondary orientation á100?.